1. Field of the Invention
The present invention relates to a photosensitive composition capable of changing the property by reaction upon irradiation with actinic ray or radiation, a pattern-forming method using the photosensitive composition, and the compounds used in the photosensitive composition. More specifically, the invention relates to a photosensitive composition for use in a manufacturing process of semiconductors, e.g., IC, the manufacture of circuit substrates for liquid crystals, thermal heads and the like, and other photo-fabrication processes, lithographic printing plates, and acid-hardening compositions, and also the invention relates to a pattern-forming process using the photosensitive composition, and the compounds used in the photosensitive composition.
2. Description of the Related Art
Chemical amplification resist compositions are pattern-forming materials capable of generating an acid at the area irradiated with actinic ray such as a far ultraviolet ray or radiation, changing the solubility in a developer of the irradiated area with the actinic ray or radiation and the solubility of the non-irradiated area by the reaction with the acid as a catalyst, and forming a pattern on a substrate.
When a KrF excimer laser is used as the exposure light source, resins having poly(hydroxystyrene) that is small in absorption in the region of 248 nm as a fundamental skeleton are mainly used, so that a high sensitivity, high resolution and good pattern is formed as compared with conventionally used naphthoquinonediazide/novolak resins.
On the other hand, when a light source of further shorter wavelength, e.g., an ArF excimer laser (193 nm), is used as the exposure light source, since compounds having an aromatic group substantially show large absorption in the region of 193 nm, resists containing a resin having a highly transparent alicyclic hydrocarbon structure have been developed for an ArF excimer laser.
Various compounds have been found as to acid generators that are main constitutional components of chemical amplification resists, e.g., triaryl sulfonium salts and arylalkyl sulfonium salts are reported (e.g., refer to JP-A-2000-275845 and JP-A-10-48814).
As generating acids, e.g., in JP-A-2002-131897 and JP-A-2003-149812, specific fluorinated organic sulfonic acids are used. In JP-T-11-501909 (The term “JP-T” as used herein refers to a “published Japanese translation of a PCT application”.), JP-A-2002-268223 and JP-A-2003-246786, imido anion acid generators capable of generating highly acidic imido upon irradiation with actinic ray or radiation are used.
However, these compounds are still insufficient in various points and the improvement in line edge roughness, pattern profile and the like is required.
In the optical microscope, as a technique of enhancing resolution, a method of filling in between a projection lens and a sample with a liquid having a high refractive index (hereinafter referred to as “immersion liquid”), i.e., an immersion method is conventionally known.
As “the effect of immersion”, resolution and the depth of focus can be expressed by the following expressions in the case of immersion, with λ0 as the wavelength of the exposure light in the air, n as the refractive index of immersion liquid to the air, and NA0=sin θ with θ as convergence half angle of the ray of light:Resolution=k1·(λ0/n)/NA0 Depth of focus=±k2·(λ0/n)/NA02 
That is, the effect of immersion is equivalent to the case of using exposure wavelength of the wavelength of 1/n. In other words, in the case of the projection optical system of the same NA, the depth of focus can be made n magnifications by immersion. This is effective for every pattern form, and further, it is possible to combine an immersion method with super resolution techniques such as a phase shift method and a transformation lighting method now under discussion.
The example of the apparatus applying this effect to the transfer of a micro-fine image pattern of a semiconductor element are introduced in JP-A-57-153433 (the term “JP-A” as used herein refers to an “unexamined published Japanese patent application”) and JP-A-7-220990.
The latest technical advancement of immersion exposure is reported in SPIE Proc., 4688, 11 (2002), J. Vac. Sci. Tecnol. B, 17 (1999), SPIE Proc., 3999, 2 (2000), and WO 2004/077158. When an ArF excimer laser is used as the light source, it is thought that pure water (having a refractive index of 1.44 at 193 nm) is most promising as the immersion liquid in the light of the safety in handling, the transmittance and the refractive index at 193 nm. When an F2 excimer laser is used as the light source, a solution containing fluorine is discussed from the balance of the transmittance and the refractive index at 157 nm, but a sufficiently satisfactory solution from the viewpoint of the environmental safety and at the point of refractive index has not been found yet. From the extent of the effect of immersion and the degree of completion of resist, it is thought that immersion exposure technique will be carried on an ArF exposure apparatus earliest.
It is appointed that when a chemical amplification resist is applied to immersion exposure, the resist layer is brought into contact with the immersion liquid at the time of exposure, so that the resist layer decomposes and ingredients that adversely influence the immersion liquid ooze from the resist layer. WO 2004/068242 discloses that resist performance decomposes by the immersion of a resist for ArF exposure in water before and after exposure and appoints this is a problem in immersion exposure.